In the case of buying/selling a product or the like via a network, people often use a virtual shopping mall as a system supporting sales transactions.
In a transaction using a virtual shopping mall, in the case of making an order and, after that, modifying the order (before completion of settlement) between parties of the transaction (seller and purchaser), usually, direct negotiation is performed between the parties of the transaction by telephone, a mail, or the like. A virtual shopping mall management system which manages and runs the virtual shopping mall is not involved.